Question

Which of the following is a chemical property of hydrogen?
A. It is monoatomic.
B. It is less dense than air.
C. It is odourless.
D. It is colourless.
E. It combusts in the presence of oxygen.

Answer 1

Hint: Hydrogen is the most easily available element in the universe. It is available in the sun and also among most of the stars, and the Jupiter planet is composed mainly of hydrogen. Hydrogen is available in the greatest quantities as water on Earth. Hydrogen is diatomic in nature. It is the smallest chemical element as it contains only 1 proton in its nucleus.

Complete step by step answer:
Hydrogen is the chemical element having the symbol H and atomic number equal to 1. The atomic weight of Hydrogen is 1.008, it is the lightest weight element in the periodic table. Hydrogen is the most available chemical substance in the whole universe, consisting around 75% of all baryonic mass.
At normal temperature and atmospheric pressure, hydrogen is not toxic, non-metallic, odourless, tasteless, colourless, and highly combustible diatomic gas having the molecular formula $H_2$. Hydrogen is also available on Earth as the type of chemical compounds such as hydrocarbons and water.
Hydrogen, as the lightest existing gas (around 7% the density of air), looks to be the most correct gas for lifting. It is easily available and produced in large quantities, for an example the water-gas shift reaction, however hydrogen has few drawbacks: Hydrogen is highly flammable.
Hence, Except Option A, all other options are correct.

So Options B,C,D and E are correct.

Note:
By observing the hint and question, the question can be easily answered. Hydrogen is useful in fuel cells to produce electricity, or power and heat. Now, hydrogen is mostly used in petroleum refining and fertilizer production, as transportation and utilities are the emerging markets.